Gear selection in motor-vehicle gearboxes is generally carried out by moving selector rings axially between the gears on the mainshaft of the gearbox (the selector rings may have other than a truly ring configuration, for example that of a sleeve or boss, but the common term "ring" will be used herein). These movements are brought about through selector forks which extend to the selector rings from outside the compass of the gears and which are caused to slide parallel to the mainshaft in dependence upon which of the gears is to be selected. The selector forks draw the selector rings along the mainshaft to engage and disengage the gears, and whereas this known form of selector mechanism, is generally satisfactory, it does have disadvantages, especially in the context of competition motoring, where precision gear-changing is to be achieved.